Boston police chief: Bombers had more attacks planned; explosives may be out there

One of them is dead and the other is lying in a hospital bed, but authorities say the brothers responsible for the deadly Boston Marathon bombing had more attacks planned had they not been stopped, the city's top police officer said Sunday.

But even though the two men are no longer believed to be a threat, Boston police Commissioner Ed Davis said law enforcement can't be certain there aren't additional explosives somewhere in the city.

"It's possible, but we have already searched the locations that are directly connected with the two bombers. They clearly had other explosives," Commissioner Davis said on "Fox News Sunday."

"We feel they had plans to use those explosives," he added.

One of the brothers, 19-year-old Dzhokhar Tsarnaev, remains in "serious but stable" condition in a Boston-area hospital, Commissioner Davis said. At this point, he is in "no condition to be interrogated," but that process will be handled by a team of FBI agents once the alleged terrorist is able, according to the police commissioner.

The other suspected bomber, 26-year-old Tamerlan Tsarnaev, was killed in a gunfight with police Thursday night.

Dzhokhar Tsarnaev was wounded in that exchange and spent the next 24 hours huddled in a boat in Watertown.